The present invention relates to a gas filtration media and, in particular, to a gas filtration media, with reduced initial pressure drops and higher dust or dirt holding capacities. The polymeric fibers forming the filtration media are made from a polymer which includes a nucleating agent and/or an electrostatic charging enhancer. The nucleating agent and/or electrostatic charging enhancer present in the polymer facilitate(s) the formation and collection of discrete fibers during the fiberization process through the maintenance of fiber integrity.
Filtration media for filtering solid and liquid aerosol particles from gas streams, such as air streams are frequently made from mats of meltblown polymeric fibers. The polymeric fibers forming these mats typically have a mean diameter between 0.5 and 15 microns and when collected during the fiberization process, these fine diameter fibers tend to adhere, bond or otherwise at least partially meld into each other; lose their discrete nature; and form a less fibrous, more sheet-like material than would otherwise occur if the fibers maintained their integrity. This melding of the polymeric fibers into each other to reduce the fibrous nature of the mat being collected to form a filtration media increases the initial pressure drop across the filtration media and decreases the dust or dirt holding capacity of the filtration media formed from the mat. The increase in the initial pressure drop across the filtration media and the reduced dust or dirt holding capacity of the filtration media increase the operating costs for such filtration media and require more frequent replacement of the filtration media. Thus, there has been a need to provide mats of more discrete meltblown polymeric fibers to increase the resiliency and loft of the filtration media made from the mats and reduce the initial pressure drop across the filtration media while increasing the dust or dirt holding capacity of such filtration media.